This invention relates to the sterile protection of hollow bore steel needles before, between and after uses with dental and medical syringes, and the prevention of accidental needlesticks in healthcare workers during use.
The evolution of bacterial resistance to many kinds of skin-borne and bloodborne infections, coupled with the ever-increasing use of hollow bore steel needles in patient care, mandate improved shielding of sharp needles before and after use under the mucous membranes or skin.
Currently, dentists customarily use carpule aspirating syringes to which an initially scabbard-shielded hollow bore steel needle, sharp on each end, is attached through a fitting on the leading end of sterilized, stainless steel, reusable syringe, after manual removal of a trailing needle scabbard. Then, a medication-filled cartridge, called a carpule, is inserted into the syringe, such that the trailing end of the sharp needle penetrates a diaphragm in the leading end of the carpule. After manual removal of the leading needle scabbard covering the sharp end of the needle used for injecting medications into patients, the armed carpule aspirating syringe is used once or more for giving anesthetic injections under oral mucous membranes or deeper injections into regional nerves. The leading end of the same needle, then, remains exposed for varying periods of time, depending on the kind of dental procedure performed and number of carpules inserted during the procedure. Because it is too hazardous for dental healthcare workers to xe2x80x9crecapxe2x80x9d the leading end of needle with the originally supplied sterile scabbard, the leading needle remains bare, unless other means are provided to protect the needle from bacterial contamination and/or causing accidental needlesticks between uses. After final use, the dentist is obliged to manually remove the needle safely, or to use some kind of device provided for disposing of the needle directly into a stationary sharps container, before cleansing and sterilizing the carpule aspirating syringe for use on another patient.
Currently, hollow bore steel needles sharp on the leading end covered by a single needle scabbard and disposable medical syringes are customarily supplied in separate sterile packages or attached together in a single sterile package. When the needle scabbard is removed in order to fill the sterile syringe from a sterile medication container, the exposed needle remains bare during transport to the patient and remains bare until after use for giving an intended subcutaneous, intramuscular or intravenous injection, unless some kind of protective device other than the original needle scabbard is provided. Needle protective devices currently in use include: sleeves on syringes which slide over the needles after use, spring mechanisms which retract needles into syringes after needle use, obturaters which extend blunt tips beyond nevel bevels with activation, and needle-hub-attached spring-loaded or hinging mechanisms which lock in place after the needle is withdrawn from a patient. A problem with many of these is that the needle remains exposed from the time of attached syringe filling with medication until withdrawal from a patient.
The use of puncture-resistant hollow cones with closed apices for inserting needles attached to syringes and other kinds of sharps, such a scalpel blades, was disclosed by Shields in U.S. Pat. No. 5,558,649 (Sep. 24, 1996). The instant patent application differs from U.S. Pat. No. 5,558,649 in that the apex of the hollow cone is left open and coned to reversibly wedge impact the scabbard of a standard dental anesthetic needle or a standard medical injection needle, along with the needle held in a hub which slip fits into the trailing open end of the needle scabbard. In effect, this eliminates the use of a scabbard fitting the trailing end of a dental anesthetic needle or a sterile package for dispensation of a medical needle not attached to a syringe. The original needle scabbard, then, becomes the needle shield.
A computer-based patent search for a similar graduated hollow cone with an open leading end and means for sterile closure of both ends, as well as reversibly connecting the hollow needle to the bore of a standard dental carpule or the bore of a standard medical syringe; and doing so inside the sterile mid-portion of the graduated hollow cone, proved negative. Monoject(trademark) provides dental and medical syringes pre-attached to needles enclosed in hollow cones which look similar externally. However, internal wedge-impaction of the syringe into the conical holder for the syringe and needle, and use of the needle scabbard to reversibly attach the needle to the syringe inside of the conical holder are not claimed
The objects of this invention are to provide simple cost-effective means for preventing cross-infections between patients and healthcare workers during the customary use of standard dental and medical hollow bore steel needles attached to syringes, as described in the Abstract. The magnitude of the problem is exemplified by the following statistics.
5-6 billion hollow bore steel needles are used annually during patient care in the USA. 600 million of these are needles sharp on each end used for giving dental anesthesia.
Annually 1-2 million Americans suffer from serious hospital acquired infections, most of which stem from needle injections. Blood stream infections, 25% fatal and costing an average of $33,000 per infection, account for 400,000 of such infections annually.
Annually some of eight million American healthcare workers suffer an estimated 600,000 to 800,000 accidental needlesticks, 0.3% resulting in HIV/AIDS infection since 1981. The rate of transmission of hepatitis B virus infection from an infected patient to a healthcare worker via a single accidental needlestick is estimated to be 6% to 30%. The rate of transmission of hepatitis C virus infection from an infected patient to a healthcare worker is currently estimated to 1.8% per accidental needle stick. Although vaccines have been developed to prevent HBV infections, there is no cure for HIV, HBV or HCV infections.
In health care facilities, patients are intentionally stuck with needles for injecting medications or withdrawing blood at the rate of 4-5 billion times annually.
The thrust of recent healthcare legislation has been toward protecting healthcare workers from accidental needlesticks. Never-the-less, patients and taxpayers pay for the needles.